Coolant in Subarus

What about switching entirely to DexCool? Would this be a problem

First - it's fairly difficult to completely flush out a system. Second - I doubt it'll cause much of a problem if a full flush is done before filling. I think the coagulation thing has been way overblown. I've converted to Dex-Cool with no ill effects in an older car.

However - I'd probably just go to the dealer an get the factory coolant to be on the safe side for my WRX.

Hi,

My experience is that one should stick with what came from the factory: "green" standard type or "orange" extended-life (Dexcool) type. I've experienced leakage in older engines switching to Dexcool, even after a complete flushing. The coagulation issue is something that came up after I quit using the Dexcool type. I live in a part of SoCal that gets pretty hot, and the Dexcool seemed to run a tiny bit cooler, but not enough to warrant the potential problems.

It used to be you just put coolant in the cooling system, ATF in automatic transmissions, etc., and didn't worry, but with changes in specs for many fluids, I'd follow Edward Hayes' idea and use OEM coolant from the dealer at least during the warranty period, along with Subaru's "treatment" to maintain head gasket warranty if your car is one of those affected. Naturally, YMMV on these issues.

Regardless of your choice, be sure to mix your coolant with DISTILLED water! That will go a long way toward keeping your cooling system clean.

Rick

Except that, at least in Canada, there is no OEM coolant. I talked to two different dealers and they both thought I was crazy. They use Laurentide brand.

So have I, no problems.

In that case, I'd use what the dealers do.

Rick

My dealer doesn't have "official" Subaru coolant, just whatever they happen to get from their supplier. Personally, I just use whatever I can get from the local automotive parts store. If your going to maintain a 30k drain and refill schedule I really don't see any benefit with going with DexCool.

Just my .02.

-Kurt

y_p_w wrote:

As far as I see it, the biggest enemy of the radiators in Japanese makes are silicate corrosion inhibitors. Silicates inevitably come out of suspension, and may clog up the small passages in these radiators. Most Japanese makers use a silicate/borate-free coolant with phosphates as corrosion inhibitors.

These seem to be the types of OEM coolants out there:

**Japanese standard: No silicates or borates. High levels of phosphate corrosion inhibitors.

**Japanese extended life: similar to Dex-Cool or other OAT coolants. May contain phosphates.

**Extended-life organic acid technology (OAT) coolants: Dex-Cool is the prime example. No silicates, borates, nitrates, nitrites, or phosphates. Some have called into question how effective they are given that they rely on organic acid corrosion inhibitors alone.

**Hybrid OAT coolants: Chysler and Zerex G-05. Similar to OAT coolant, but with low-silicate levels as a corrosion inhibitor. Seems to be used by Ford, Daimler-Chrysler, and other European carmakers. No phospates. Phosphate-free seems to be important in Europe, where high mineral content water is the norm. Phosphates apparently cause the minerals to precipitate out and becomes abrasive.

Aftermarket coolants:

**Traditional silicated: Yellow prestone, Peak, Zerex, etc. This seems to be the type generally used in American cars with changes up to 30K miles or 2 years. I can't think of any volume carmaker who would still use this kind of coolant as OEM. The newer versions allegedly contain less silicates than in years past.

**Low-tox propylene glycol: Prestone low-tox, Sierra, etc. Propylene glycol is essentially non-toxic in small amounts and is used in food and medicines. It has lower boilover temp and a higher freezing temp.